Heretofore, various silicones such as a silicone oil with a low viscosity, a silicone gum with a high degree of polymerization, and the like have been blended in a cosmetic as a cosmetic raw material. The silicone elastomer particles obtained by crosslinking a crosslinkable organopolysiloxane have also been used as a cosmetic raw material.
The silicone elastomer particles can be obtained by, for example, dispersing an uncrosslinked crosslinkable organopolysiloxane in water, heating the dispersion to carry out crosslinking, and then drying. However, in the preparation of the silicone elastomer particles in accordance with the aforementioned method, a drying step for removing water is necessary, and the preparation process is complicated.
Therefore, blending the silicone elastomer particles in the state of an aqueous dispersion in which the particles are dispersed in water in a cosmetic has also been proposed. However, in the aqueous dispersion of the silicone elastomer particles, an emulsifier used in order to disperse the uncrosslinked crosslinkable organopolysiloxane in water is usually present. If the aqueous dispersion in which the emulsifier remains is blended in a cosmetic, feeling to the touch of the cosmetic may be impaired, depending on the types of the emulsifiers.
On the other hand, an oil-based dispersion in which silicone elastomer particles are dispersed in an oil such as a silicone oil or the like has been known as a cosmetic raw material. The aforementioned oil-based dispersion can be produced by crosslinking an organopolysiloxane in an oil. However, as long as the aforementioned oil-based dispersion contains the silicone elastomer with an increased elastic force in the form of solid particles, a cosmetic blending the aforementioned oil-based dispersion exhibits a poor smooth sensation, and poor compatibility with the skin. In addition, the aforementioned oil-based dispersion is a non-uniform system in which the particles are dispersed in the oil, and for this reason, even if the dispersion is mixed with other oil agents, particles may remain. Therefore, a uniform oil phase cannot be obtained.
In addition, a paste or a gel obtained by absorbing an oil such as a silicone oil or the like in a silicone elastomer has also been known as a cosmetic raw material. For example, Japanese Unexamined Patent Application, First Publication No. 2009-185296 describes a paste in which an organopolysiloxane having a specific crosslinking structure contains an oil and swells. However, the paste or gel is not a liquid, and for this reason, it is difficult to uniformly mix with a liquid oil that is used in a cosmetic in many cases. Therefore, if the aforementioned paste or gel is blended in a cosmetic, the paste or gel may remain in the form of particles in the oil phase. In this case, the same problem as that described in the case of the aforementioned oil-based dispersion containing the silicone elastomer in the form of solid particles may occur.
On the other hand, Published Japanese Translation No. 2010-502780 of the PCT International Application discloses a branched polysiloxane, but fails to describe use thereof in a cosmetic.